Recently, there has been an increased interest in using more than one fuel type to fuel a vehicle engine such that different fuels can be used under different engine operating conditions.
A system for selectively fuelling a vehicle with multiple fuel tanks via a single filler port fitting is described in U.S. patent application Ser. No. 12/402,999, (concurrently filed herewith), which is hereby incorporated by reference. Different fuel types may be stored in each fuel tank, by detection of a fuel type in a fuel reservoir and subsequent direction of the fuel to a selected fuel tank.
The Applicants have recognized that prior fuel system leak diagnostic systems typically include a fuel pressure sensor for measuring pressure in a fuel tank or fuel system, and do not account for the various additional parts of a vehicle with multiple fuel tanks that may contribute to errors in diagnostic testing. Conventionally, as complexity is increased in a vehicle system, additional sensors are placed throughout a system to achieve accurate monitoring of operating conditions, thereby increasing complexity and costs.
Thus, fuel systems and methods for controlling fuel systems in a vehicle with multiple fuel tanks are herein provided. An exemplary vehicle fuel system includes a first fuel tank including a first pressure sensor, and a second fuel tank. The system may further include a fuel tank isolation valve positioned to selectively decouple the first fuel tank and the second fuel tank. The system may further include an electronic controller configured to identify which of the first fuel tank and second fuel tank includes a fuel system leak by selectively decoupling the first fuel tank and the second fuel tank via the fuel tank isolation valve, responsive to an identification of the fuel system leak.
By selectively decoupling multiple tanks in a fuel system, fuel system leak diagnostics can be performed without the addition of multiple pressure sensors (although multiple sensors may be used, if desired). In one example, by systematically isolating a first fuel tank from a second fuel tank and correlating system response with an expected response, a fuel system leak, if present, can be localized and identified even when more information is available about one tank than another. Further, fuel types can be kept separate in multiple fuel tanks while maintaining accuracy of fuel system leak diagnostics.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.